HP65 Strip Reader

[John Kruppenbach]

I have a hp 65 and awhile ago I had a problem with the mag strip reader. It seems the drive wheel had deteriorated over the years and had become somewhat gummy. I found a replacement in a microcassette (capstan/pinch roller)based answering machine. BUT now the calculator will not energize the motor when a card is placed into the reader. I've verified the motor is functioning by independantly energizing it with 3 vdc. I've also checked the switches that detect a card in the reader, those reed-type switches that are activated with a ball. I was wondering does the motor get powered through some semiconductor device or is it directly through the reed switch? I lost some of the balls to the switches and had to replace them with beads purchased at a craft store. HELP MY HP johnk

[Erik Wahlin]

There are a couple of reasons it may not be working. You need to make sure that the finger (Reed) switches are actually making contact. You need to trace out the contact points and use an ohm meter and see if the first switch (the first switch that the card makes contact with)which turns the motor on is making contact when a card is inserted. Sometimes I have found if you push the card far in it energizes another switch which sometimes turns the motor on. (I hope this discussion about the switches makes sense). If you find that the switch does not properly make contact, you need to use a jewlers screwdriver and turn in the switch adjusting screw. This makes the long finger switch bend toward the contact region. It may be that the balls you are using are not the proper diameter. The other problem is usually a loose wire to the circuit card reader circuit board.There are a black and red wire connecting to the circuit board, and a black and red wie going to the motor.

[Matthew Riehl]

You can visually check to see if the switches are making contact with the circuit board. The switches sit in a shallow recess in the top of the two pieces that holds the card reader.

Hold the pieces up so that your eyes are even with the top edge (you should not be able to see into the recess and should be able to see light through the card slot) and looking from the right side. They should be screwed together for this. Slowly insert a card into the slot from the normal side, the side you are looking from. You should see a total of four fingers lift above the surface of the plastic material. The first one that comes up is the one that tells the motor to start, it is towards the right side. Once the card hits the wheel, you will have to push harder to move it through without the motor but you won't hurt the card or the reader.

If you see less than four fingers pop up, adjust the finger that doesn't so that it comes up out of the well. Just make sure that it is also fully down in the well when no card is present. I had a card reader that wouldn't write to the cards and was able to diagnose it this way. I would also guess that the diameter of the replacement balls are to small.

Best of luck with it.